Seesaw-Like Cervical Ossification of Posterior Longitudinal Ligament.

Ossification of posterior longitudinal ligament (OPLL) is a pathological process in which lamellar bone is deposited at the posterior longitudinal ligament and can lead to a limited range of cervical motion and spinal cord compression. A 64-year-old man presented with a 10-month history of worsening clumsiness in the hands and impaired gait, and he occasionally had a feeling of an electric shock in the limbs when the neck was flexed. Physical examination revealed atrophy of the intrinsic hand muscles, rapid reflexes in the lower extremities, and positive Hoffman sign and Babinski sign results. Seesaw-like OPLL was observed on hyperextension and hyperflexion x-rays, which also showed that the OPLL involved the spinal canal; laminoplasty and laminectomy were not recommended for this specific type of OPLL, even though the K-line was positive on both x-rays.